diff --git a/src/module-info.java b/src/module-info.java
index 915833c..a8b9e86 100644
--- a/src/module-info.java
+++ b/src/module-info.java
@@ -3,5 +3,5 @@
     exports org.joni.constants;
     exports org.joni.exception;
 
-    requires org.jruby.jcodings;
+    requires transitive org.jruby.jcodings;
 }
\ No newline at end of file
diff --git a/src/org/joni/ApplyCaseFold.java b/src/org/joni/ApplyCaseFold.java
index 32a1fd1..ca10da1 100644
--- a/src/org/joni/ApplyCaseFold.java
+++ b/src/org/joni/ApplyCaseFold.java
@@ -28,6 +28,7 @@
 final class ApplyCaseFold implements ApplyAllCaseFoldFunction {
 
     // i_apply_case_fold
+    @Override
     public void apply(int from, int[]to, int length, Object o) {
         ApplyCaseFoldArg arg = (ApplyCaseFoldArg)o;
 
diff --git a/src/org/joni/BitSet.java b/src/org/joni/BitSet.java
index d3108f6..fe8d3c1 100644
--- a/src/org/joni/BitSet.java
+++ b/src/org/joni/BitSet.java
@@ -110,6 +110,7 @@ private static int log2(int n){
     }
 
     private static final int BITS_TO_STRING_WRAP = 4;
+    @Override
     public String toString() {
         StringBuilder buffer = new StringBuilder();
         buffer.append("BitSet");
diff --git a/src/org/joni/ByteCodeMachine.java b/src/org/joni/ByteCodeMachine.java
index a360520..d25ea6d 100644
--- a/src/org/joni/ByteCodeMachine.java
+++ b/src/org/joni/ByteCodeMachine.java
@@ -57,6 +57,7 @@ class ByteCodeMachine extends StackMachine {
         this.code = regex.code;
     }
 
+    @Override
     public void interrupt() {
         interrupted = true;
         // might have no effect on the executing thread but worth a try
@@ -153,6 +154,7 @@ private boolean stringCmpIC(int caseFlodFlag, int s1, IntHolder ps2, int mbLen,
         return true;
     }
 
+    @Override
     protected final int matchAt(int _range, int _sstart, int _sprev, boolean interrupt) throws InterruptedException {
         range = _range;
         sstart = _sstart;
@@ -444,7 +446,7 @@ private final int executeSb(final boolean checkThreadInterrupt) throws Interrupt
 
     private void handleInterrupted(final boolean checkThreadInterrupt) throws InterruptedException {
         if (interrupted || (checkThreadInterrupt && Thread.currentThread().isInterrupted())) {
-            Thread.currentThread().interrupted();
+            Thread.interrupted();
             throw new InterruptedException();
         }
         interruptCheckEvery = Math.min(interruptCheckEvery << 1, MAX_INTERRUPT_CHECK_EVERY);
diff --git a/src/org/joni/CodeRangeBuffer.java b/src/org/joni/CodeRangeBuffer.java
index 2eebb6e..fc6d908 100644
--- a/src/org/joni/CodeRangeBuffer.java
+++ b/src/org/joni/CodeRangeBuffer.java
@@ -89,6 +89,7 @@ public void writeCodePoint(int pos, int b) {
         if (used < u) used = u;
     }
 
+    @Override
     public CodeRangeBuffer clone() {
         return new CodeRangeBuffer(this);
     }
@@ -374,6 +375,7 @@ public static CodeRangeBuffer andCodeRangeBuff(CodeRangeBuffer bbuf1, boolean no
         return pbuf;
     }
 
+    @Override
     public String toString() {
         StringBuilder buf = new StringBuilder();
         buf.append("CodeRange");
diff --git a/src/org/joni/MultiRegion.java b/src/org/joni/MultiRegion.java
index 46e925b..baf0eb4 100644
--- a/src/org/joni/MultiRegion.java
+++ b/src/org/joni/MultiRegion.java
@@ -32,10 +32,12 @@ public MultiRegion(int begin, int end) {
         this.begEnd = new int[]{begin, end};
     }
 
+    @Override
     public final int getNumRegs() {
         return begEnd.length / 2;
     }
 
+    @Override
     public MultiRegion clone() {
         MultiRegion region = new MultiRegion(getNumRegs());
         System.arraycopy(begEnd, 0, region.begEnd, 0, begEnd.length);
@@ -43,22 +45,27 @@ public MultiRegion clone() {
         return region;
     }
 
+    @Override
     public int getBeg(int index) {
         return begEnd[index * 2];
     }
 
+    @Override
     public int setBeg(int index, int value) {
         return begEnd[index * 2] = value;
     }
 
+    @Override
     public int getEnd(int index) {
         return begEnd[index * 2 + 1];
     }
 
+    @Override
     public int setEnd(int index, int value) {
         return begEnd[index * 2 + 1] = value;
     }
 
+    @Override
     void clear() {
         Arrays.fill(begEnd, REGION_NOTPOS);
     }
diff --git a/src/org/joni/NameEntry.java b/src/org/joni/NameEntry.java
index 55c34b3..40caaea 100644
--- a/src/org/joni/NameEntry.java
+++ b/src/org/joni/NameEntry.java
@@ -79,6 +79,7 @@ public void addBackref(int backRef) {
         }
     }
 
+    @Override
     public String toString() {
         StringBuilder buff = new StringBuilder(new String(name, nameP, nameEnd - nameP) + " ");
         if (backNum == 0) {
diff --git a/src/org/joni/Region.java b/src/org/joni/Region.java
index ace0442..4507c45 100644
--- a/src/org/joni/Region.java
+++ b/src/org/joni/Region.java
@@ -33,6 +33,7 @@ public static Region newRegion(int begin, int end) {
         return new SingleRegion(begin, end);
     }
 
+    @Override
     public abstract Region clone();
 
     public abstract int getNumRegs();
@@ -45,6 +46,7 @@ public static Region newRegion(int begin, int end) {
 
     public abstract int setEnd(int index, int value);
 
+    @Override
     public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("Region: \n");
diff --git a/src/org/joni/Search.java b/src/org/joni/Search.java
index 5c729fd..9616d5a 100644
--- a/src/org/joni/Search.java
+++ b/src/org/joni/Search.java
@@ -297,7 +297,7 @@ final int search(Matcher matcher, byte[]text, int textP, int adjustText, int tex
                 s--;
             }
             return -1;
-        };
+        }
     };
 
     static final Forward BM_FORWARD = new Forward() {
diff --git a/src/org/joni/SingleRegion.java b/src/org/joni/SingleRegion.java
index a99bf3b..3064264 100644
--- a/src/org/joni/SingleRegion.java
+++ b/src/org/joni/SingleRegion.java
@@ -32,36 +32,43 @@ public SingleRegion(int begin, int end) {
         this.end = end;
     }
 
+    @Override
     public int getNumRegs() {
         return 1;
     }
 
+    @Override
     public SingleRegion clone() {
         SingleRegion region = new SingleRegion(beg, end);
         if (getCaptureTree() != null) region.setCaptureTree(getCaptureTree().cloneTree());
         return region;
     }
 
+    @Override
     public int getBeg(int index) {
         if (index != 0) throw new IndexOutOfBoundsException(""+index);
         return beg;
     }
 
+    @Override
     public int setBeg(int index, int value) {
         if (index != 0) throw new IndexOutOfBoundsException(""+index);
         return beg = value;
     }
 
+    @Override
     public int getEnd(int index) {
         if (index != 0) throw new IndexOutOfBoundsException(""+index);
         return end;
     }
 
+    @Override
     public int setEnd(int index, int value) {
         if (index != 0) throw new IndexOutOfBoundsException(""+index);
         return end = value;
     }
 
+    @Override
     void clear() {
         beg = end = REGION_NOTPOS;
     }
diff --git a/src/org/joni/StackMachine.java b/src/org/joni/StackMachine.java
index 2782600..71adff2 100644
--- a/src/org/joni/StackMachine.java
+++ b/src/org/joni/StackMachine.java
@@ -132,6 +132,7 @@ private void stateCheckMark() {
 
     // STATE_CHECK_BUFF_INIT
     private static final int STATE_CHECK_BUFF_MALLOC_THRESHOLD_SIZE = 16;
+    @Override
     protected final void stateCheckBuffInit(int strLength, int offset, int stateNum) {
         if (stateNum > 0 && strLength >= Config.CHECK_STRING_THRESHOLD_LEN) {
             int size = ((strLength + 1) * stateNum + 7) >>> 3;
@@ -156,6 +157,7 @@ protected final void stateCheckBuffInit(int strLength, int offset, int stateNum)
         }
     }
 
+    @Override
     protected final void stateCheckBuffClear() {
         stateCheckBuff = null;
         stateCheckBuffSize = 0;
@@ -549,7 +551,7 @@ protected final int nullCheckMemStRec(int id, int s) {
                                         isNull = 0;
                                         break;
                                     } else if (endp != s) {
-                                        isNull = -1;; /* empty, but position changed */
+                                        isNull = -1; /* empty, but position changed */
                                     }
                                 }
                                 k++;
diff --git a/src/org/joni/UnsetAddrList.java b/src/org/joni/UnsetAddrList.java
index eb0bf64..c0b64f7 100644
--- a/src/org/joni/UnsetAddrList.java
+++ b/src/org/joni/UnsetAddrList.java
@@ -55,6 +55,7 @@ public void fix(Regex regex) {
         }
     }
 
+    @Override
     public String toString() {
         StringBuilder value = new StringBuilder();
         if (num > 0) {
diff --git a/src/org/joni/WarnCallback.java b/src/org/joni/WarnCallback.java
index 60bf578..d79d6a1 100644
--- a/src/org/joni/WarnCallback.java
+++ b/src/org/joni/WarnCallback.java
@@ -24,12 +24,14 @@
  */
 public interface WarnCallback {
     WarnCallback DEFAULT = new WarnCallback() {
-        public void warn(String message) {
+       @Override
+       public void warn(String message) {
             System.err.println(message);
         }
     };
 
     WarnCallback NONE = new WarnCallback() {
+        @Override
         public void warn(String message) {
         }
     };
diff --git a/src/org/joni/ast/Node.java b/src/org/joni/ast/Node.java
index fc3b50e..759f091 100644
--- a/src/org/joni/ast/Node.java
+++ b/src/org/joni/ast/Node.java
@@ -44,7 +44,7 @@ protected void setChild(Node tgt){
     protected Node getChild(){
         // default definition
         return null;
-    };
+    }
 
     public void replaceWith(Node with) {
         with.parent = parent;
@@ -59,6 +59,7 @@ public String getAddressName() {
         return getName() + ":0x" + Integer.toHexString(System.identityHashCode(this));
     }
 
+    @Override
     public final String toString() {
         StringBuilder s = new StringBuilder();
         s.append("<" + getAddressName() + " (" + (parent == null ? "NULL" : parent.getAddressName())  + ")>");
diff --git a/test/org/joni/test/TestInterrupt.java b/test/org/joni/test/TestInterrupt.java
index 0656dc4..48034ec 100755
--- a/test/org/joni/test/TestInterrupt.java
+++ b/test/org/joni/test/TestInterrupt.java
@@ -58,8 +58,10 @@ public Syntax syntax() {
     }
 
     @org.junit.Test
+    @Override
     public void test() throws Exception {
         interruptAfter(new InterruptibleRunnable() {
+            @Override
             public void run() throws InterruptedException {
                 x2s("a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
                         "aaaaaaaaaaaaaaaaaaaaaaaaaaaaa", 0, 0);
@@ -69,6 +71,7 @@ public void run() throws InterruptedException {
         final int status[] = new int[1];
 
         interruptAfter(new InterruptibleRunnable() {
+            @Override
             public void run() throws InterruptedException {
                 try {
                     x2s("a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
diff --git a/test/org/joni/test/TestU.java b/test/org/joni/test/TestU.java
index f0ca360..f8b027f 100755
--- a/test/org/joni/test/TestU.java
+++ b/test/org/joni/test/TestU.java
@@ -69,13 +69,16 @@ private String uconv(byte []bytes, int len) {
         return sb.toString();
     }
 
+    @Override
     protected String repr(byte[]bytes) {
         return uconv(bytes, ulen(bytes));
     }
 
+    @Override
     protected int length(byte[]bytes) {
         return ulen(bytes);
     }
+
     @Override
     public void test() throws Exception {
         x2s("\000\000", "\000\000", 0, 0);